1. Field of the Invention
The present invention relates generally to a wireless network and more particularly to a wireless network for communicating information and commands between the various components of manufacturing equipment or manufacturing systems.
2. Description of Related Art
Many of today's manufacturing equipment includes a wide variety or sensors and actuators that respectively provide data concerning a manufacturing process and control various components used in the manufacturing process. Theses sensors and actuators are connected to local controllers that are in turn, connected to a central control system. In some instances, the sensors and actuators are connected directly to the central control system. Importantly, in most conventional manufacturing equipment, the various components communicate normally using a physical connection for communications, such as a twisted pair of wires, or other cabling. The use of communication cables is expensive in both design and in implementation.
The cable layout design typically involves specialized software to ensure that the physical layout of the cables is correct and that the ambient conditions are correct. Moreover, the cable needs to have the correct specification and shielding to ensure reliability, both physical and communicative. The cables themselves are also expensive, with a good portion of the cost residing in the connectors. The connectors are also problematic in terms of reliability both during maintenance and in normal operation.
For a semiconductor process tool, for example, there are many different devices to which a central controller is connected. A large number of physical ports are used to connect each of the components of the process tool. In addition, not all of the various devices have the same type of communication medium or protocol. All of these factors conspire to drive the cost of the system up and the reliability down, particularly since many of the communications are point-to-point serial.